This invention relates to forming surfaces on optical elements.
Miniature, monolithic, solid state lasers, such as the microchip laser, are produced by placing a length of gain material within a short resonant cavity. Typically, the resonant cavity is created by forming mirrored surfaces on the gain material itself. For this type of resonant cavity to be effective, the gain medium must be polished flat and parallel on two opposing sides. While such lasers can be formed if the surface of the gain medium is slightly convex, they can not be formed if the gain material has a concave surface or if the surfaces are not parallel such that shape of the gain material has the form of a wedge between the two surfaces.
Referring to FIGS. 1 and 1A, using conventional polishing techniques, a relatively restricted region can be produced on each polished wafer 10 which has the required parallelism. Towards the edges of the wafer the material becomes wedge shaped (shown exaggerated for clarity), and microchip lasers taken from that portion of the wafer do not form a proper resonant cavity with this shape. In addition, the cutting of a large wafer into sections relieves stress at the surface of the wafer, causing the sections to distort. This can cause a low yield of usable sections because the distortion tends to destroy the parallel relationship between the surfaces.